This invention relates particularly to multiply glazed window and door systems of the type which include breathing openings in the sash to communicate with the insulating air chamber between the glass panels or glazings, for the purpose of providing the desired, limited, air circulation which provides certain advantages over sealed windows. Such systems permit a sufficient, yet restricted, air circulation so as to prevent steaming or condensation without appreciably effecting the insulating qualities of the unit. While functioning very well in this regard, windows and doors of this character, with breathing openings, are sometimes prevented from operating satisfactorily by insects such as wasps, which find the breathing passages attractive for nesting and the deposit of their eggs. While a variety of breather devices and perforated members for insect proofing have been proposed in the past, as illustrated in the following prior art patents, none have, to my knowledge, found any acceptance in the trade, or enjoyed any appreciable commercial success:
______________________________________ 1,703,230 Gillar 2,905,072 Oswald 2,202,694 Haux 3,429,084 Brewer 2,231,514 Verhagen 4,282,691 Risdon 2,233,952 Lipsett 4,528,787 Rittinge 2,345,643 Verhagen ______________________________________